animal development — Introduction the processes that lead eventually to the formation of a new animal starting from cells derived from one or more parent individuals. Development thus occurs following the process by which a new generation of organisms is produced by … Universalium

vertebrate — /verr teuh brit, brayt /, adj. 1. having vertebrae; having a backbone or spinal column. 2. belonging or pertaining to the Vertebrata (or Craniata), a subphylum of chordate animals, comprising those having a brain enclosed in a skull or cranium… … Universalium

yolk — also yoke noun Etymology: Middle English yolke, from Old English geoloca, from geolu yellow more at yellow Date: before 12th century 1. a. the yellow spheroidal mass of stored food that forms the inner portion of the egg of a bird or reptile and… … New Collegiate Dictionary

Nemertea — For the Romanian village that bears this name, see Gura Teghii. Nemertea … Wikipedia